Lightweight polymer ammunition cartridge casings

ABSTRACT

One embodiment of the present invention provides a polymeric ammunition cartridge and methods of making and using the same. The cartridge includes a substantially cylindrical insert connected to a substantially cylindrical polymeric middle body. The substantially cylindrical insert includes a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash hole positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface. The substantially cylindrical polymeric middle body includes a substantially cylindrical polymeric bullet-end and a substantially cylindrical polymeric coupling end connected by a powder chamber, wherein the substantially cylindrical polymeric coupling end extends over the substantially cylindrical coupling element and covers a circumferential surface of the primer flash hole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent Application No.61/456,664, filed Nov. 10, 2010 the contents of which is incorporated byreference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of ammunition,specifically to compositions of matter and methods of making and usingpolymeric ammunition cartridge casings.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

INCORPORATION-BY-REFERENCE OF MATERIALS FILED ON COMPACT DISC

None.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with lightweight polymer cartridge casing ammunition.Conventional ammunition cartridge casings for rifles and machine guns,as well as larger caliber weapons, are made from brass, which is heavy,expensive, and potentially hazardous. There exists a need for anaffordable lighter weight replacement for brass ammunition cartridgecases that can increase mission performance and operationalcapabilities. Lightweight polymer cartridge casing ammunition must meetthe reliability and performance standards of existing fielded ammunitionand be interchangeable with brass cartridge casing ammunition inexisting weaponry. Reliable cartridge casings manufacture requiresuniformity (e.g., bullet seating, bullet-to-casing fit, casing strength,etc.) from one cartridge to the next in order to obtain consistentpressures within the casing during firing prior to bullet and casingseparation to create uniformed ballistic performance. Plastic cartridgecasings have been known for many years but have failed to providesatisfactory ammunition that could be produced in commercial quantitieswith sufficient safety, ballistic, handling characteristics, and survivephysical and natural conditions to which it will be exposed during theammunition's intended life cycle; however, these characteristics havenot been achieved.

For example, U.S. patent application Ser. No. 11/160,682 discloses abase for a cartridge casing body for an ammunition article, the basehaving an ignition device; an attachment device at one end thereof, theattachment device being adapted to the base to a cartridge casing body;wherein the base is made from plastic, ceramic, or a composite material.

U.S. Pat. No. 7,610,858 discloses an ammunition cartridge assembled froma substantially cylindrical polymeric cartridge casing body defining acasing headspace with an open projectile-end and an end opposing theprojectile-end, wherein the casing body has a substantially cylindricalinjection molded polymeric bullet-end component with opposing first andsecond ends, the first end of which is the projectile-end of the casingbody and the second end has a male or female coupling element; and acylindrical polymeric middle body component with opposing first andsecond ends, wherein the first end has a coupling element that is a matefor the projectile-end coupling element and joins the first end of themiddle body component to the second end of the bullet-end component, andthe second end is the end of the casing body opposite the projectile endand has a male or female coupling element; and a cylindrical cartridgecasing head-end component with an essentially closed base end with aprimer hole opposite an open end with a coupling element that is a matefor the coupling element on the second end of the middle body and joinsthe second end of the middle body component to the open end of thehead-end component; wherein the middle body component is formed from amaterial more ductile than the material head-end component is formedfrom but equal or less ductile than the material the bullet-endcomponent is formed from. Methods for assembling ammunition cartridgesand ammunition cartridges having the headspace length larger than thecorresponding headspace length of the chamber of the intended weaponmeasured at the same basic diameter for the cartridge casing withoutbeing so large as to jam the weapon or otherwise interfere with itsaction are also disclosed.

Shortcomings of the known methods of producing plastic or substantiallyplastic ammunition include the possibility of the projectile beingpushed into the cartridge casing, the bullet pull being too light suchthat the bullet can fall out, the bullet pull being too insufficient tocreate sufficient chamber pressure, the bullet pull not being uniformfrom round to round, and portions of the cartridge casing breaking offupon firing causing the weapon to jam or damage or danger whensubsequent rounds are fired or when the casing portions themselvesbecome projectiles. To overcome the above shortcomings, improvements incartridge case design and performance polymer materials are needed.

BRIEF SUMMARY OF THE INVENTION

One embodiment of the present invention provides a polymeric ammunitioncartridge. The cartridge includes a substantially cylindrical insertconnected to a substantially cylindrical polymeric middle body. Thesubstantially cylindrical insert includes a top surface opposite abottom surface and a substantially cylindrical coupling element thatextends from the bottom surface, a primer recess in the top surface thatextends toward the bottom surface, a primer flash hole positioned in theprimer recess to extend through the bottom surface, and a flange thatextends circumferentially about an outer edge of the top surface. Thesubstantially cylindrical polymeric middle body includes a substantiallycylindrical polymeric bullet-end and a substantially cylindricalpolymeric coupling end connected by a powder chamber, wherein thesubstantially cylindrical polymeric coupling end extends over thesubstantially cylindrical coupling element and covers a circumferentialsurface of the primer flash hole. Other embodiments include the primerinserted into the primer recess, the charge located in the powderchamber, and/or a bullet or projectile.

In one embodiment the substantially cylindrical polymeric middle body isformed from a ductile polymer, more preferably a nylon polymer. In oneembodiment the substantially cylindrical polymeric middle body is formedfrom a fiber-reinforced polymeric composite. In one embodiment thefiber-reinforced polymeric composite contains between about 10 and about70 wt % glass fiber fillers, mineral fillers, or mixtures thereof. Inone embodiment the substantially cylindrical polymeric bullet-end andbullet are further welded or bonded together.

The substantially cylindrical polymeric bullet-end may include a forwardopening end having a first and a second mechanical interlock forengagement between the forward opening end and a bullet. In oneembodiment the forward opening end includes two or more canneluresformed on an outer circumferential surface of the forward opening end.In one embodiment the forward opening end comprises one, two or moreannular rings that mate with one, two or more corresponding annulargrooves positioned on the bullet. The forward opening end is crimped sothat a polymeric material flows into an annular groove of a bullet. Inone embodiment the bullet is adhesively fitted to the forward openingend; however, in other embodiment, the bullet is fitted to the forwardopening end by welding or bonding together using solvent, adhesive,spin-welding, vibration-welding, ultrasonic-welding or laser-weldingtechniques.

In one embodiment the substantially cylindrical polymeric bullet-endincludes a cannelure or mechanical interlock for engagement between theforward opening end and a bullet at the shoulder end of the forwardopening end. Although the mechanical interlock is located in the lowerportion of the bullet at the shoulder end it may also be located at anyposition from the entrance or the end of the cylindrical polymericbullet-end. Furthermore, the mechanical interlock/cannelure may include1, 2, 3, 4, 5, or more mechanical interlocks/cannelures. Thesubstantially cylindrical polymeric bullet-end may be connected to thebullet through an adhesive or weld. In addition, a combination ofadhesives or welds, etc and 1, 2, 3, 4, 5, or more mechanicalinterlocks/cannelures may be used.

The substantially cylindrical polymeric bullet-end may include a forwardopening end having a first and a second mechanical interlock forengagement between the forward opening end and a bullet. In oneembodiment the forward opening end includes two or more canneluresformed on an outer circumferential surface of the forward opening end.In one embodiment the forward opening end comprises one, two or moreannular rings that mate with one, two or more corresponding annulargrooves positioned on the bullet. The forward opening end is crimped sothat a polymeric material flows into an annular groove of a bullet. Inone embodiment the bullet is adhesively fitted to the forward openingend; however, in other embodiment, the bullet is fitted to the forwardopening end by welding or bonding together using solvent, adhesive,spin-welding, vibration-welding, ultrasonic-welding or laser-weldingtechniques.

In one embodiment the substantially cylindrical polymeric middle bodyincludes a polymers selected from the group consisting of polyurethaneprepolymer, cellulose, fluoro-polymer, ethylene inter-polymer alloyelastomer, ethylene vinyl acetate, nylon, polyether imide, polyesterelastomer, polyester sulfone, polyphenyl amide, polypropylene,polyvinylidene fluoride or thermoset polyurea elastomer, acrylics,homopolymers, acetates, copolymers, acrylonitrile-butadinen-styrene,thermoplastic fluoro polymers, inomers, polyamides, polyamide-imides,polyacrylates, polyatherketones, polyaryl-sulfones, polybenzimidazoles,polycarbonates, polybutylene, terephthalates, polyether imides,polyether sulfones, thermoplastic polyimides, thermoplasticpolyurethanes, polyphenylene sulfides, polyethylene, polypropylene,polysulfones, polyvinylchlorides, styrene acrylonitriles, polystyrenes,polyphenylene, ether blends, styrene maleic anhydrides, polycarbonates,allyls, aminos, cyanates, epoxies, phenolics, unsaturated polyesters,bismaleimides, polyurethanes, silicones, vinylesters, urethane hybrids,polyphenylsulfones, copolymers of polyphenylsulfones withpolyethersulfones or polysulfones, copolymers of poly-phenylsulfoneswith siloxanes, blends of polyphenylsulfones with polysiloxanes,poly(etherimide-siloxane) copolymers, blends of polyetherimides andpolysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers.

The forward opening end comprises a neck with a plurality of internalstructures for supporting a bullet. The substantially cylindricalcoupling element is a male coupling element with a straight skirtinterlock surface that tapers to a smaller diameter at the forwardportion on the skirt tip to mate with a female coupling element of thesubstantially cylindrical polymeric coupling end. In one embodiment thepolymeric ammunition cartridge further includes a diffuser positioned inthe primer recess comprising a diffuser flash hole aligned with theprimer flash hole.

Another embodiment of the polymeric ammunition cartridge having adiffuser of the present invention includes a substantially cylindricalinsert, a diffuser, and a substantially cylindrical polymeric middlebody. The substantially cylindrical insert includes a top surfaceopposite a bottom surface and a substantially cylindrical couplingelement that extends from the bottom surface, a primer recess in the topsurface that extends toward the bottom surface, a primer flash holepositioned in the primer recess to extend through the bottom surface,and a flange that extends circumferentially about an outer edge of thetop surface. The diffuser positioned in the primer recess comprising adiffuser flash hole aligned with the primer flash hole. Thesubstantially cylindrical polymeric middle body includes a substantiallycylindrical polymeric bullet-end and a substantially cylindricalpolymeric coupling end connected by a powder chamber, wherein thesubstantially cylindrical polymeric coupling end extends over thesubstantially cylindrical coupling element and covers a circumferentialsurface of the primer flash hole. The diffuser has a primer flash holewith a flash hole lip extending into a bore of the primer flash hole.

Another embodiment of the polymeric ammunition cartridge of the presentinvention includes a substantially cylindrical insert having a topsurface opposite a bottom surface and a substantially cylindricalcoupling element that extends from the bottom surface, a primer recessin the top surface that extends toward the bottom surface, a primerflash hole positioned in the primer recess to extend through the bottomsurface, and a flange that extends circumferentially about an outer edgeof the top surface; a substantially cylindrical polymeric middle bodycomprising a substantially cylindrical polymeric bullet-end and asubstantially cylindrical polymeric coupling end connected by a powderchamber, wherein the substantially cylindrical polymeric coupling endextends over the substantially cylindrical coupling element and coversan circumferential surface of the primer flash hole; and a substantiallycylindrical polymeric bullet-end upper portion comprising a bullet-endcoupling element connected to the substantially cylindrical polymericbullet-end and a forward opening end to engage a bullet.

Another embodiment of the polymeric ammunition cartridge of the presentinvention includes a metal insert for a polymeric ammunition cartridgehaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface. In other embodiments the polymericammunition cartridge, further includes a diffuser positioned in theprimer recess comprising a diffuser flash hole aligned with the primerflash hole.

Another embodiment of the polymeric ammunition cartridge of the presentinvention includes a polymer insert for a polymeric ammunition cartridgehaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface. In other embodiments the polymericammunition cartridge, further includes a diffuser positioned in theprimer recess.

Still another embodiment includes a method of forming a polymericammunition cartridge by providing a substantially cylindrical inserthaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface, forming a substantially cylindricalpolymeric middle body comprising a substantially cylindrical polymericbullet-end and a substantially cylindrical polymeric coupling endconnected by a powder chamber, connecting the substantially cylindricalpolymeric coupling end to the substantially cylindrical couplingelement; and covering circumferentially an interior surface of theprimer flash hole. The method further includes the step of positioning adiffuser comprising a diffuser flash hole in the primer recess andaligning the diffuser flash hole with the primer flash hole.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 depicts a side, cross-sectional view of a polymeric cartridgecase according to one embodiment of the present invention;

FIG. 2 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case according to one embodiment of the presentinvention;

FIG. 3 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case lacking the aperture coating;

FIGS. 4 a and 4 b depict images of a catastrophic failure of thepolymeric cartridge case of FIG. 3;

FIG. 5 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention;

FIG. 6 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention;

FIG. 7 depicts a side, cross-sectional view of a polymeric cartridgecase having a diffuser according to one embodiment of the presentinvention;

FIG. 8 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case having a diffuser according to one embodimentof the present invention;

FIGS. 9 a-9 h depict diffuser according to a different embodiment of thepresent invention;

FIG. 10 depicts an exploded view of the polymeric cartridge casing; and

FIG. 11 depicts a view of the substantially cylindrical open-endedpolymeric bullet-end having a shoulder forming chamber neck and abullet.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of this invention, a number of terms aredefined below. Terms defined herein have meanings as commonly understoodby a person of ordinary skill in the areas relevant to the presentinvention. Terms such as “a”, “an” and “the” are not intended to referto only a singular entity, but include the general class of which aspecific example may be used for illustration. The terminology herein isused to describe specific embodiments of the invention, but their usagedoes not delimit the invention, except as outlined in the claims.

Reliable cartridge manufacture requires uniformity from one cartridge tothe next in order to obtain consistent ballistic performance. Amongother considerations, proper bullet seating and bullet-to-casing fit isrequired. In this manner, a desired pressure develops within the casingduring firing prior to bullet and casing separation. Historically,bullets employ a cannelure, which is a slight annular depression formedin a surface of the bullet at a location determined to be the optimalseating depth for the bullet. In this manner, a visual inspection of acartridge could determine whether or not the bullet is seated at theproper depth. Once the bullet is inserted into the casing to the properdepth, one of two standard procedures is incorporated to lock the bulletin its proper location. One method is the crimping of the entire end ofthe casing into the cannelure. A second method does not crimp the casingend; rather the bullet is pressure fitted into the casing.

The polymeric ammunition cartridges of the present invention are of acaliber typically carried by soldiers in combat for use in their combatweapons. The present invention is not limited to the described caliberand is believed to be applicable to other calibers as well. Thisincludes various small and medium caliber munitions, including 5.56 mm,7.62 mm and .50 caliber ammunition cartridges, as well as medium/smallcaliber ammunition such as 380 caliber, 38 caliber, 9 mm, 10 mm, 20 mm,25 mm, 30 mm, 40 mm, 45 caliber and the like. The cartridges, therefore,are of a caliber between about 0.05 and about 5 inches. Thus, thepresent invention is also applicable to the sporting goods industry foruse by hunters and target shooters.

FIG. 1 depicts a side, cross-sectional view of a polymeric cartridgecase according to one embodiment of the present invention. A cartridge10 suitable for use with high velocity rifles is shown manufactured witha polymer casing 12 showing a powder chamber 14 with projectile (notshown) inserted into the forward end opening 16. Polymer casing 12 has asubstantially cylindrical open-ended polymeric bullet-end 18 extendingfrom forward end opening 16 rearward to opposite end 20. The bullet-endcomponent 18 may be formed with coupling end 22 formed on end 20.Coupling end 22 is shown as a female element, but may also be configuredas a male element in alternate embodiments of the invention. The forwardend of bullet-end component 18 has a shoulder 24 forming chamber neck26. The bullet-end component typically has a wall thickness betweenabout 0.003 and about 0.200 inches and more preferably between about0.005 and more preferably between about 0.150 inches about 0.010 andabout 0.050 inches.

The middle body component 28 is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Couplingelement 30, as shown may be configured as a male element, however, allcombinations of male and female configurations is acceptable forcoupling elements 30 and coupling end 22 in alternate embodiments of theinvention. Coupling end 22 of bullet-end component 18 fits about andengages coupling element 30 of a substantially cylindrical insert 32.The substantially cylindrical insert 32 includes a substantiallycylindrical coupling element 30 extending from a bottom surface 34 thatis opposite a top surface 36. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34. A primer flash hole40 is located in the primer flash hole 40 and extends through the bottomsurface 34 into the powder chamber 14. The coupling end 22 extends thepolymer through the primer flash hole 40 to form an aperture coating 42while retaining a passage from the top surface 36 through the bottomsurface 34 and into the powder chamber 14 to provide support andprotection about the primer flash hole 40. When contacted the couplingend 22 interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip 44 to form a physical interlock betweensubstantially cylindrical insert 32 and middle body component 28.Polymer casing 12 also has a substantially cylindrical open-ended middlebody component 28. The middle body component extends from a forward endopening 16 to coupling element 22. The middle body component typicallyhas a wall thickness between about 0.003 and about 0.200 inches and morepreferably between about 0.005 and more preferably between about 0.150inches about 0.010 and about 0.050 inches.

The bullet-end 16, middle body 18 and bottom surface 34 define theinterior of powder chamber 14 in which the powder charge (not shown) iscontained. The interior volume of powder chamber 14 may be varied toprovide the volume necessary for complete filling of the chamber 14 bythe propellant chosen so that a simplified volumetric measure ofpropellant can be utilized when loading the cartridge. Either aparticulate or consolidated propellant can be used.

The substantially cylindrical insert 32 also has a flange 46 cut thereinand a primer recess 38 formed therein for ease of insertion of theprimer (not shown). The primer recess 38 is sized so as to receive theprimer (not shown) in an interference fit during assembly. A primerflash hole 40 communicates through the bottom surface 34 ofsubstantially cylindrical insert 32 into the powder chamber 14 so thatupon detonation of primer (not shown) the powder in powder chamber 14will be ignited.

Projectile (not shown) is held in place within chamber case neck 26 atforward opening 16 by an interference fit. Mechanical crimping of theforward opening 16 can also be applied to increase the bullet pullforce. The bullet (not shown) may be inserted into place following thecompletion of the filling of powder chamber 14. Projectile (not shown)can also be injection molded directly onto the forward opening 16 priorto welding or bonding together using solvent, adhesive, spin-welding,vibration-welding, ultrasonic-welding or laser-welding techniques. Thewelding or bonding increases the joint strength so the casing can beextracted from the hot gun casing after firing at the cook-offtemperature.

The bullet-end and bullet components can then be welded or bondedtogether using solvent, adhesive, spin-welding, vibration-welding,ultrasonic-welding or laser-welding techniques. The welding or bondingincreases the joint strength so the casing can be extracted from the hotgun casing after firing at the cook-off temperature. An optional firstand second annular grooves (cannelures) may be provided in thebullet-end in the interlock surface of the male coupling element toprovide a snap-fit between the two components. The cannelures formed ina surface of the bullet at a location determined to be the optimalseating depth for the bullet. Once the bullet is inserted into thecasing to the proper depth to lock the bullet in its proper location.One method is the crimping of the entire end of the casing into thecannelures.

The bullet-end and middle body components can then be welded or bondedtogether using solvent, adhesive, spin-welding, vibration-welding,ultrasonic-welding or laser-welding techniques. The welding or bondingincreases the joint strength so the casing can be extracted from the hotgun casing after firing at the cook-off temperature.

FIG. 2 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case according to one embodiment of the presentinvention. A portion of a cartridge suitable for use with high velocityrifles is shown manufactured with a polymer casing 12 showing a powderchamber 14. Polymer casing 12 has a substantially cylindrical oppositeend 20. The bullet-end component 18 may be formed with coupling end 22formed on end 20. Coupling end 22 is shown as a female element, but mayalso be configured as a male element in alternate embodiments of theinvention. The middle body component (not shown) is connected to asubstantially cylindrical coupling element 30 of the substantiallycylindrical insert 32. Coupling element 30, as shown may be configuredas a male element, however, all combinations of male and femaleconfigurations is acceptable for coupling elements 30 and coupling end22 in alternate embodiments of the invention. Coupling end 22 fits aboutand engages coupling element 30 of a substantially cylindrical insert32. The substantially cylindrical insert 32 includes a substantiallycylindrical coupling element 30 extending from a bottom surface 34 thatis opposite a top surface 36. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34. A primer flash hole40 is located in the primer recess 28 and extends through the bottomsurface 34 into the powder chamber 14. The coupling end 22 extends thepolymer through the primer flash hole 40 to form an aperture coating 42while retaining a passage from the top surface 36 through the bottomsurface 34 and into the powder chamber 14 to provide support andprotection about the primer flash hole 40. When contacted the couplingend 22 interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip 44 to form a physical interlock betweensubstantially cylindrical insert 32 and middle body component 28.Polymer casing 12 also has a substantially cylindrical open-ended middlebody component 28.

FIG. 3 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case lacking the aperture coating (not shown).

FIGS. 4 a and 4 b depict images of a catastrophic failure of thepolymeric cartridge case of FIG. 3. Other polymeric cartridge case wastested and resulted in catastrophic failure with the rounds blowing themagazine out of the weapon and fragmenting the metal insert and lodgingthe polymer case in the chamber. The examination of the catastrophicfailure revealed the tearing of the polymer at the top of the insert. Asa result, in some embodiments the height of the insert was reduced by0.020″ to reduce the tearing and frequency of catastrophic failures.Further examination, revealed that the polymer at the flash hole of thebase was separating from the insert. One embodiment locks the polymerinto the flash hole by extending the polymer into the flash hole. Inaddition, the raised area was removed, the diameter of the flash holewas opened, and the primer side was counter bored. Other embodiments mayincorporate all, one, or a combination of 2 or more of these elements tostop the gas from separating the polymer from the insert that wascreating combustion between the insert and the polymer.

FIG. 5 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention. A portion of a cartridge suitable for use withhigh velocity rifles is shown manufactured with a polymer casing 12showing a powder chamber 14. Polymer casing 12 has a substantiallycylindrical opposite end 20. The bullet-end component 18 may be formedwith coupling end 22 formed on end 20. Coupling end 22 is shown as afemale element, but may also be configured as a male element inalternate embodiments of the invention. The middle body component (notshown) is connected to a substantially cylindrical coupling element 30of the substantially cylindrical insert 32. Coupling element 30, asshown may be configured as a male element, however, all combinations ofmale and female configurations is acceptable for coupling elements 30and coupling end 22 in alternate embodiments of the invention. Couplingend 22 fits about and engages coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30, extending from a bottomsurface 34 that is opposite a top surface 36. Located in the top surface36 is a primer recess 38 that extends toward the bottom surface 34. Aprimer flash hole 40 is located in the primer flash hole 40 and extendsthrough the bottom surface 34 into the powder chamber 14. The couplingend 22 extends the polymer through the primer flash hole 40 to form anaperture coating 42 while retaining a passage from the top surface 36through the bottom surface 34 and into the powder chamber 14 to providesupport and protection about the primer flash hole 40. When contactedthe coupling end 22 interlocks with the substantially cylindricalcoupling element 30, through the coupling element 30 that extends with ataper to a smaller diameter at the tip 44 to form a physical interlockbetween substantially cylindrical insert 32 and middle body component28. Polymer casing 12 also has a substantially cylindrical open-endedmiddle body component 28. The substantially cylindrical opposite end 20or anywhere within the powder chamber 14 may include one or more ribs 48on the surface. The number of ribs 48 will depend on the specificapplication and desire of the manufacture but may include 1, 2, 3, 4, 56, 7, 8, 9, 10, or more ribs. In the counter bore, the polymer washaving difficulty filling this area due to the fact that the polymerused has fillers in it, and needed to be reblended during molding. Oneembodiment includes six ribs 48 to create turbulence in the flow of thepolymer, thus allowing the material to fill the counter bore.

FIG. 6 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention. One embodiment that reduces bellowing of theinsert includes a shortened insert and angled coupling element 30 insideof the insert. In addition, the raised portion of the polymer at theflash hole was removed, the internal polymer wall was lowered and angledto match the insert and the internal ribs were lengthened.

A portion of a cartridge suitable for use with high velocity rifles isshown manufactured with a polymer casing 12 showing a powder chamber 14.Polymer casing 12 has a substantially cylindrical opposite end 20. Thebullet-end component 18 may be formed with coupling end 22 formed on end20. Coupling end 22 is shown as a female element, but may also beconfigured as a male element in alternate embodiments of the invention.The middle body component (not shown) is connected to a substantiallycylindrical coupling element 30 of the substantially cylindrical insert32. Coupling element 30, as shown may be configured as a male element,however, all combinations of male and female configurations isacceptable for coupling elements 30 and coupling end 22 in alternateembodiments of the invention. Coupling end 22 fits about and engagescoupling element 30 of a substantially cylindrical insert 32. Thesubstantially cylindrical insert 32 includes a substantially cylindricalcoupling element 30 extending from a bottom surface 34 that is oppositea top surface 36. Located in the top surface 36 is a primer recess 38that extends toward the bottom surface 34. A primer flash hole 40 islocated in the primer flash hole 40 and extends through the bottomsurface 34 into the powder chamber 14. The coupling end 22 extends thepolymer through the primer flash hole 40 to form an aperture coating 42while retaining a passage from the top surface 36 through the bottomsurface 34 and into the powder chamber 14 to provide support andprotection about the primer flash hole 40. When contacted the couplingend 22 interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip 44 to form a physical interlock betweensubstantially cylindrical insert 32 and middle body component 28.Polymer casing 12 also has a substantially cylindrical open-ended middlebody component 28. The substantially cylindrical opposite end 20 oranywhere within the powder chamber 14 may include one or more ribs 48 onthe surface. The number of ribs 48 will depend on the specificapplication and desire of the manufacture but may include 1, 2, 3, 4, 56, 7, 8, 9, 10, or more ribs. In the counter bore, the polymer washaving difficulty filling this area due to the fact that the polymerused has fillers in it, and needed to be reblended during molding. Oneembodiment includes six ribs 48 to create turbulence in the flow of thepolymer, thus allowing the material to fill the counter bore. Anotherembodiment of the instant invention is a shortened insert and angledcoupling element 30 inside of the insert. In addition, raised portionsof the polymer at the flash hole, lowered and angled the internalpolymer wall to match the insert and lengthened the internal ribs.

FIG. 7 depicts a side, cross-sectional view of a polymeric cartridgecase having a diffuser according to one embodiment of the presentinvention. The diffuser 50 is a device that is used to divert theaffects of the primer off of the polymer and directing it to the flashhole. The affects being the impact from igniting the primer as far aspressure and heat. A cartridge 10 suitable for use with high velocityrifles is shown manufactured with a polymer casing 12 showing a powderchamber 14 with projectile (not shown) inserted into the forward endopening 16. Polymer casing 12 has a substantially cylindrical open-endedpolymeric bullet-end 18 extending from forward end opening 16 rearwardto the opposite end 20. The bullet-end component 18 may be formed withcoupling end 22 formed on end 20. Coupling end 22 is shown as a femaleelement, but may also be configured as a male element in alternateembodiments of the invention. The forward end of bullet-end component 18has a shoulder 24 forming chamber neck 26.

The middle body component 28 is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Couplingelement 30, as shown may be configured as a male element, however, allcombinations of male and female configurations is acceptable forcoupling elements 30 and coupling end 22 in alternate embodiments of theinvention. Coupling end 22 of bullet-end component 18 fits about andengages coupling element 30 of a substantially cylindrical insert 32.The substantially cylindrical insert 32 includes a substantiallycylindrical coupling element 30 extending from a bottom surface 34 thatis opposite a top surface 36. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34. A primer flash hole40 is located in the primer flash hole 40 and extends through the bottomsurface 34 into the powder chamber 14. The coupling end 22 extends thepolymer through the primer flash hole 40 to form an aperture coating 42while retaining a passage from the top surface 36 through the bottomsurface 34 and into the powder chamber 14 to provides support andprotection about the primer flash hole 40. When contacted the couplingend 22 interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip 44 to form a physical interlock betweensubstantially cylindrical insert 32 and middle body component 28.Polymer casing 12 also has a substantially cylindrical open-ended middlebody component 28. The middle body component extends from a forward endopening 16 to coupling element 22. Located in the top surface 36 is aprimer recess 38 that extends toward the bottom surface 34 with adiffuser 50 positioned in the primer recess 38. The diffuser 50 includesa diffuser aperture 52 that aligns with the primer flash hole 40. Thediffuser 50 is a device that is used to divert the affects of the primer(not shown) off of the polymer. The affects being the impact fromigniting the primer as far as pressure and heat to divert the energy ofthe primer off of the polymer and directing it to the flash hole.

FIG. 8 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case having a diffuser according to one embodimentof the present invention. A portion of a cartridge suitable for use withhigh velocity rifles is shown manufactured with a polymer casing 12showing a powder chamber 14. Polymer casing 12 has a substantiallycylindrical opposite end 20. The bullet-end component 18 may be formedwith coupling end 22 formed on end 20. Coupling end 22 is shown as afemale element, but may also be configured as a male element inalternate embodiments of the invention. The middle body component (notshown) is connected to a substantially cylindrical coupling element 30of the substantially cylindrical insert 32. Coupling element 30, asshown may be configured as a male element, however, all combinations ofmale and female configurations is acceptable for coupling elements 30and coupling end 22 in alternate embodiments of the invention. Couplingend 22 fits about and engages coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30 extending from a bottomsurface 34 that is opposite a top surface 36. Located in the top surface36 is a primer recess 38 that extends toward the bottom surface 34. Aprimer flash hole 40 is located in the primer flash hole 40 and extendsthrough the bottom surface 34 into the powder chamber 14. The couplingend 22 extends the polymer through the primer flash hole 40 to form anaperture coating 42 while retaining a passage from the top surface 36through the bottom surface 34 and into the powder chamber 14 to providessupport and protection about the primer flash hole 40. When contactedthe coupling end 22 interlocks with the substantially cylindricalcoupling element 30, through the coupling element 30 that extends with ataper to a smaller diameter at the tip 44 to form a physical interlockbetween substantially cylindrical insert 32 and middle body component28. Polymer casing 12 also has a substantially cylindrical open-endedmiddle body component 28. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34 with a diffuser 50positioned in the primer recess 38. The diffuser 50 includes a diffuseraperture 52 and a diffuser aperture extension 54 that aligns with theprimer flash hole 40. The diffuser 50 is a device that is used to divertthe affects of the primer (not shown) off of the polymer. The affectsbeing the impact from igniting the primer as far as pressure and heat todivert the energy of the primer off of the polymer and directing it tothe flash hole. The diffuser 50 can be between 0.004 to 0.010 inches inthickness and made from half hard brass. For example, the diffuser 50can be between 0.005 inches thick for a 5.56 diffuser 50. The OD of thediffuser for a 5.56 or 223 case is 0.173 and the ID is 0.080. TheDiffuser could be made of any material that can withstand the energyfrom the ignition of the primer. This would include steel, stainless,cooper, aluminum or even an engineered resin that was injection moldedor stamped. The Diffuser can be produce in T shape by drawing thematerial with a stamping and draw die. In the T Diffuser the center ringcan be 0.005 to 0.010 tall and the OD is 0.090 and the ID 0.080.

FIGS. 9 a-9 h depict different embodiment of the diffuser of the presentinvention.

FIG. 10 depicts an exploded view of the polymeric cartridge casing. Acartridge 10 suitable for use with high velocity rifles is shownmanufactured with a middle body component 28 having a substantiallycylindrical open-ended polymeric bullet-end 18. The substantiallycylindrical open-ended polymeric bullet-end 18 has a shoulder 24 formingchamber neck 26 and a bullet 56 inserted therein. The substantiallycylindrical insert 32 also has a flange 46 cut therein and a primerrecess (not shown) formed therein for ease of insertion of the primer(not shown).

FIG. 11 depicts a view of the substantially cylindrical open-endedpolymeric bullet-end 18 has a shoulder 24 forming chamber neck 26 and abullet (not shown). One embodiment includes modifications to strengthenthe neck of the mouth 60 and to the internal base area 62 to reduce nosetearing and lodging in the chamber. The substantially cylindricalopen-ended polymeric bullet-end 18 illustrates a lock 58 (e.g.,0.030×0.003) and added a step to allow for the lock 58 to flex outduring firing. Polymer was added to the external area to strengthen theneck of the mouth 60 and to the internal base area 62. The interferenceof the bullet to the neck was increased by adding polymer to the insideof the neck 64 and the exit lock modified by adding an angle to the rim66.

The polymeric and composite casing components may be injection molded.Polymeric materials for the bullet-end and middle body components musthave propellant compatibility and resistance to gun cleaning solventsand grease, as well as resistance to chemical, biological andradiological agents. The polymeric materials must have a temperatureresistance higher than the cook-off temperature of the propellant,typically about 320° F. The polymeric materials must haveelongation-to-break values that to resist deformation under interiorballistic pressure as high as 60,000 psi in all environments(temperatures from about −65 to about 320° F. and humidity from 0 to100% RH). According to one embodiment, the middle body component iseither molded onto or snap-fit to the casing head-end component afterwhich the bullet-end component is snap-fit or interference fit to themiddle body component. The components may be formed from high-strengthpolymer, composite or ceramic.

Examples of suitable high strength polymers include composite polymermaterial including a tungsten metal powder, nylon 6/6, nylon 6, andglass fibers; and a specific gravity in a range of 3-10. The tungstenmetal powder may be 50%-96% of a weight of the bullet body. The polymermaterial also includes about 0.5-15%, preferably about 1-12%, and mostpreferably about 2-9% by weight, of nylon 6/6, about 0.5-15%, preferablyabout 1-12%, and most preferably about 2-9% by weight, of nylon 6, andabout 0.5-15%, preferably about 1-12%, and most preferably about 2-9% byweight, of glass fibers. It is most suitable that each of theseingredients be included in amounts less than 10% by weight. Thecartridge casing body may be made of a modified ZYTEL resin, availablefrom E.I. DuPont De Nemours Co., a modified 612 nylon resin, modified toincrease elastic response.

Examples of suitable polymers include polyurethane prepolymer,cellulose, fluoro-polymer, ethylene inter-polymer alloy elastomer,ethylene vinyl acetate, nylon, polyether imide, polyester elastomer,polyester sulfone, polyphenyl amide, polypropylene, polyvinylidenefluoride or thermoset polyurea elastomer, acrylics, homopolymers,acetates, copolymers, acrylonitrile-butadinen-styrene, thermoplasticfluoro polymers, inomers, polyamides, polyamide-imides, polyacrylates,polyatherketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates,polybutylene, terephthalates, polyether imides, polyether sulfones,thermoplastic polyimides, thermoplastic polyurethanes, polyphenylenesulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides,styrene acrylonitriles, polystyrenes, polyphenylene, ether blends,styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates,epoxies, phenolics, unsaturated polyesters, bismaleimides,polyurethanes, silicones, vinylesters, or urethane hybrids. Examples ofsuitable polymers also include aliphatic or aromatic polyamide,polyeitherimide, polysulfone, polyphenylsulfone, poly-phenylene oxide,liquid crystalline polymer and polyketone. Examples of suitablecomposites include polymers such as polyphenylsulfone reinforced withbetween about 30 and about 70 wt %, and preferably up to about 65 wt %of one or more reinforcing materials selected from glass fiber, ceramicfiber, carbon fiber, mineral fillers, organo nanoclay, or carbonnanotube. Preferred reinforcing materials, such as choppedsurface-treated E-glass fibers provide flow characteristics at theabove-described loadings comparable to unfilled polymers to provide adesirable combination of strength and flow characteristics that permitthe molding of head-end components. Composite components can be formedby machining or injection molding. Finally, the cartridge case mustretain sufficient joint strength at cook-off temperatures. Morespecifically, polymers suitable for molding of the projectile-endcomponent have one or more of the following properties: Yield or tensilestrength at −65° F.>10,000 psi Elongation-to-break at −65° F.>15% Yieldor tensile strength at 73° F.>8,000 psi Elongation-to-break at 73°F.>50% Yield or tensile strength at 320° F.>4,000 psiElongation-to-break at 320° F.>80%. Polymers suitable for molding of themiddle-body component have one or more of the following properties:Yield or tensile strength at −65° F.>10,000 psi Yield or tensilestrength at 73° F.>8,000 psi Yield or tensile strength at 320° F.>4,000psi.

Commercially available polymers suitable for use in the presentinvention thus include polyphenylsulfones; copolymers ofpolyphenylsulfones with polyether-sulfones or polysulfones; copolymersand blends of polyphenylsulfones with polysiloxanes;poly(etherimide-siloxane); copolymers and blends of polyetherimides andpolysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers; and the like. Particularlypreferred are polyphenylsulfones and their copolymers with poly-sulfonesor polysiloxane that have high tensile strength and elongation-to-breakto sustain the deformation under high interior ballistic pressure. Suchpolymers are commercially available, for example, RADEL R5800polyphenylesulfone from Solvay Advanced Polymers. The polymer can beformulated with up to about 10 wt % of one or more additives selectedfrom internal mold release agents, heat stabilizers, anti-static agents,colorants, impact modifiers and UV stabilizers.

The polymers of the present invention can also be used for conventionaltwo-piece metal-plastic hybrid cartridge case designs and conventionalshotgun shell designs. One example of such a design is an ammunitioncartridge with a one-piece substantially cylindrical polymeric cartridgecasing body with an open projectile-end and an end opposing theprojectile-end with a male or female coupling element; and a cylindricalmetal cartridge casing head-end component with an essentially closedbase end with a primer hole opposite an open end having a couplingelement that is a mate for the coupling element on the opposing end ofthe polymeric cartridge casing body joining the open end of the head-endcomponent to the opposing end of the polymeric cartridge casing body.The high polymer ductility permits the casing to resist breakage.

One embodiment includes a 2 cavity prototype mold having an upperportion and a base portion for a 5.56 case having a metal insertover-molded with a Nylon 6 (polymer) based material. In this embodimentthe polymer in the base includes a lip or flange to extract the casefrom the weapon. One 2-cavity prototype mold to produce the upperportion of the 5.56 case can be made using a stripper plate tool usingan Osco hot spur and two subgates per cavity. Another embodimentincludes a subsonic version, the difference from the standard and thesubsonic version is the walls are thicker thus requiring less powder.This will decrease the velocity of the bullet thus creating a subsonicround.

The extracting inserts is used to give the polymer case a tough enoughridge and groove for the weapons extractor to grab and pull the case outthe chamber of the gun. The extracting insert is made of 17-4 ss that ishardened to 42-45 rc. The insert may be made of aluminum, brass, cooper,steel or even an engineered resin with enough tensile strength.

The insert is over molded in an injection molded process using a nanoclay particle filled Nylon material. The inserts can be machined orstamped. In addition, an engineered resin able to withstand the demandon the insert allows injection molded and/or even transfer molded.

One of ordinary skill in the art will know that many propellant typesand weights can be used to prepare workable ammunition and that suchloads may be determined by a careful trial including initial lowquantity loading of a given propellant and the well known stepwiseincreasing of a given propellant loading until a maximum acceptable loadis achieved. Extreme care and caution is advised in evaluating newloads. The propellants available have various burn rates and must becarefully chosen so that a safe load is devised.

The description of the preferred embodiments should be taken asillustrating, rather than as limiting, the present invention as definedby the claims. As will be readily appreciated, numerous combinations ofthe features set forth above can be utilized without departing from thepresent invention as set forth in the claims. Such variations are notregarded as a departure from the spirit and scope of the invention, andall such modifications are intended to be included within the scope ofthe following claims.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the invention, and vice versa. Furthermore, compositionsof the invention can be used to achieve methods of the invention.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, MB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

1. A polymeric ammunition cartridge comprising: a substantiallycylindrical insert comprising a top surface opposite a bottom surfaceand a substantially cylindrical coupling element that extends from thebottom surface, a primer recess in the top surface that extends towardthe bottom surface, a primer flash hole positioned in the primer recessto extend through the bottom surface, and a flange that extendscircumferentially about an outer edge of the top surface; and asubstantially cylindrical polymeric middle body comprising asubstantially cylindrical polymeric bullet-end and a substantiallycylindrical polymeric coupling end connected by a powder chamber,wherein the substantially cylindrical polymeric coupling end extendsover the substantially cylindrical coupling element and covers ancircumferential surface of the primer flash hole.
 2. The polymericammunition cartridge of claim 1, wherein the substantially cylindricalpolymeric middle body is formed from a ductile polymer.
 3. The polymericammunition cartridge of claim 1, wherein the substantially cylindricalpolymeric middle body comprise a nylon polymer.
 4. The polymericammunition cartridge of claim 1, wherein the substantially cylindricalpolymeric middle body is formed from a fiber-reinforced polymericcomposite.
 5. The polymeric ammunition cartridge of claim 4, wherein thefiber-reinforced polymeric composite contains between about 10 and about70 wt % glass fiber fillers, mineral fillers, or mixtures thereof. 6.The polymeric ammunition cartridge of claim 1, wherein the substantiallycylindrical polymeric bullet-end and bullet are further welded or bondedtogether.
 7. The polymeric ammunition cartridge of claim 1, wherein thesubstantially cylindrical polymeric bullet-end comprises a forwardopening end having a first and a second mechanical interlock forengagement between the forward opening end and a bullet.
 8. Thepolymeric ammunition cartridge of claim 1, wherein the forward openingend comprises one or more cannelures formed on an outer circumferentialsurface of the forward opening end.
 9. The polymeric ammunitioncartridge of claim 1, wherein the forward opening end comprises one,two, three, or more annular rings that mate with one, two, three, ormore corresponding annular grooves positioned on the bullet.
 10. Thepolymeric ammunition cartridge of claim 1, wherein the forward openingend is crimped so that a polymeric material flows into an annular grooveof a bullet.
 11. The polymeric ammunition cartridge of claim 1, whereina bullet is adhesively fitted to the forward opening end.
 12. Thepolymeric ammunition cartridge of claim 1, wherein the substantiallycylindrical polymeric middle body comprise a polymers selected from thegroup consisting of polyurethane prepolymer, cellulose, fluoro-polymer,ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon,polyether imide, polyester elastomer, polyester sulfone, polyphenylamide, polypropylene, polyvinylidene fluoride or thermoset polyureaelastomer, acrylics, homopolymers, acetates, copolymers,acrylonitrile-butadinen-styrene, thermoplastic fluoro polymers, inomers,polyamides, polyamide-imides, polyacrylates, polyatherketones,polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene,terephthalates, polyether imides, polyether sulfones, thermoplasticpolyimides, thermoplastic polyurethanes, polyphenylene sulfides,polyethylene, polypropylene, polysulfones, polyvinylchlorides, styreneacrylonitriles, polystyrenes, polyphenylene, ether blends, styrenemaleic anhydrides, polycarbonates, allyls, aminos, cyanates, epoxies,phenolics, unsaturated polyesters, bismaleimides, polyurethanes,silicones, vinylesters, urethane hybrids, polyphenylsulfones, copolymersof polyphenylsulfones with polyethersulfones or polysulfones, copolymersof poly-phenylsulfones with siloxanes, blends of polyphenylsulfones withpolysiloxanes, poly(etherimide-siloxane) copolymers, blends ofpolyetherimides and polysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers.
 13. The polymeric ammunitioncartridge of claim 1, wherein the forward opening end comprises a neckwith a plurality of internal structures for supporting a bullet.
 14. Thepolymeric ammunition cartridge of claim 1, wherein the substantiallycylindrical coupling element is a male coupling element with a straightskirt interlock surface that tapers to a smaller diameter at the forwardportion on the skirt tip to mate with a female coupling element of thesubstantially cylindrical polymeric coupling end.
 15. The polymericammunition cartridge of claim 1, further comprising a diffuserpositioned in the primer recess comprising a diffuser flash hole alignedwith the primer flash hole.
 16. A polymeric ammunition cartridge havinga diffuser comprising: a substantially cylindrical insert comprising atop surface opposite a bottom surface and a substantially cylindricalcoupling element that extends from the bottom surface, a primer recessin the top surface that extends toward the bottom surface, a primerflash hole positioned in the primer recess to extend through the bottomsurface, and a flange that extends circumferentially about an outer edgeof the top surface; a diffuser positioned in the primer recesscomprising a diffuser flash hole aligned with the primer flash hole; anda substantially cylindrical polymeric middle body comprising asubstantially cylindrical polymeric bullet-end and a substantiallycylindrical polymeric coupling end connected by a powder chamber,wherein the substantially cylindrical polymeric coupling end extendsover the substantially cylindrical coupling element and covers ancircumferential surface of the primer flash hole.
 17. The polymericammunition cartridge of claim 16, wherein the diffuser has a primerflash hole with a flash hole lip extending into a bore of the primerflash hole.
 18. A polymeric ammunition cartridge comprising: asubstantially cylindrical insert comprising a top surface opposite abottom surface and a substantially cylindrical coupling element thatextends from the bottom surface, a primer recess in the top surface thatextends toward the bottom surface, a primer flash hole positioned in theprimer recess to extend through the bottom surface, and a flange thatextends circumferentially about an outer edge of the top surface; asubstantially cylindrical polymeric middle body comprising asubstantially cylindrical polymeric bullet-end and a substantiallycylindrical polymeric coupling end connected by a powder chamber,wherein the substantially cylindrical polymeric coupling end extendsover the substantially cylindrical coupling element and covers ancircumferential surface of the primer flash hole; and a substantiallycylindrical polymeric bullet-end upper portion comprising a bullet-endcoupling element connected to the substantially cylindrical polymericbullet-end and a forward opening end to engage a bullet.
 19. Thepolymeric ammunition cartridge of claim 18, wherein the forward openingend has one or more annular rings positioned to receive a correspondingtwo or more annular grooves in the bullet.
 20. A metal insert for apolymeric ammunition cartridge comprising: a top surface opposite abottom surface and a substantially cylindrical coupling element thatextends from the bottom surface, a primer recess in the top surface thatextends toward the bottom surface, a primer flash hole positioned in theprimer recess to extend through the bottom surface, and a flange thatextends circumferentially about an outer edge of the top surface. 21.The polymeric ammunition cartridge of claim 20, further comprising adiffuser positioned in the primer recess comprising a diffuser flashhole aligned with the primer flash hole.
 22. A method of forming apolymeric ammunition cartridge comprising the steps of: providing asubstantially cylindrical insert comprising a top surface opposite abottom surface and a substantially cylindrical coupling element thatextends from the bottom surface, a primer recess in the top surface thatextends toward the bottom surface, a primer flash hole positioned in theprimer recess to extend through the bottom surface, and a flange thatextends circumferentially about an outer edge of the top surface forminga substantially cylindrical polymeric middle body comprising asubstantially cylindrical polymeric bullet-end and a substantiallycylindrical polymeric coupling end connected by a powder chamber;connecting the substantially cylindrical polymeric coupling end to thesubstantially cylindrical coupling element; and coveringcircumferentially an interior surface of the primer flash hole.
 23. Themethod of claim 22, further comprising the step of positioning adiffuser comprising a diffuser flash hole in the primer recess andaligning the diffuser flash hole with the primer flash hole.